The present invention relates generally to operations performed in conjunction with subterranean wells and, in an embodiment described herein, more particularly provides a method and apparatus for performing a completion cleanup operation downhole.
Just prior to placing a well in production after a gravel packing operation or stimulation treatment therein, it is common practice to remove completion fluids from a hydrocarbon-bearing zone intersected by the well. In the usual situation, a substantial portion of the completion fluids in the zone are deposited there as a result of the gravel packing or stimulation treatment. If no gravel packing or stimulation treatments have been performed, then the completion fluids in the zone may be mud or other fluids introduced into the well during drilling or completion of the well. As used herein, the term "completion fluid" is used to indicate fluid which is introduced into a zone from a source other than the zone during drilling or completion of a well intersecting the zone.
Generally, the completion cleanup operation is accomplished by transporting an extensive amount of temporary production and fluid handling equipment to the well. This equipment may include temporary piping, manifolds, test heads, separators, line heaters, tanks, burner booms, etc. The temporary equipment is typically used because there is not yet any permanent production equipment installed at the well or the permanent production equipment is not designed to handle the cleanup operation.
The temporary equipment is rigged up on location and the well is flowed until all or most of the completion fluid has been removed from the hydrocarbon bearing zone. Any hydrocarbons produced in this operation may be burned off or otherwise disposed of, thereby creating safety and environmental problems. The completion fluids must also be disposed of, which is an additional environmental problem and adds to the expense of the operation.
From the foregoing, it can be seen that it would be quite desirable to provide an improved method of performing a completion cleanup operation. The improved method should not require that completion fluids and/or hydrocarbons be disposed of at the surface, and the method should be more economical, convenient to perform and safer than past cleanup operations. It is accordingly an object of the present invention to provide such an improved method, and an apparatus useful in performing the method.